Antifoggants for silver halide emulsions on a linear polyester support



United States Patent 3,287,135 ANTIFOGGANTS FOR SILVER HALIDE EMUL- SIONS ON A LINEAR POLYESTER SUPPORT Albert E. Anderson and William W. Rees, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Sept. 25, 1964, Ser. No. 399,394 9 Claims. (Cl. 96-87) This application is a continuation-in-part of our copending application Serial No. 332,258, filed December 20, 1963, and now abandoned.

This invention relates to photographic elements, and more particularly to photographic silver halide emulsions coated on polyester film base, which emulsions are protected against fog caused by contaminants in the film base.

As employed herein, fog refers to silver salt reduced during development of photographic emulsions in areas where no exposure is given, and the terms fog inhibiting agent and antifoggant refer to a compound added to an emulsion which tends to inhibit'spontane'ous growth "of fog during prolonged storage. Fog tends to increase with r time and temperature in storage conditions; it iscommon,

practice to make accelerated tests of the stability of photographic emulsions by storage at elevated temperatures. It is, of course, desirable to have emulsions as stable as possible under conditions of high temperature.

As is known, polyester films have good physical properties, such as excellent dimensional stability, which render such films highly useful as supports for photographic silver halide emulsions. However, polyester films, commonly contain various side reaction products which may be formed during synthesis of the polyester as well as catalyst residue. Some or all of these constituents may serve to fog emulsions coated on polyester supports, particularly at low humidity, even though a barrier layer such as a conventional subbing layer is interposed between the support and the emulsion coating. The fog caused by the contaminant or contaminants in polyester film is not satisfactorily inhibited by conventional fog inhibiting agents. It therefore appears desirable to provide photographic elements comprising silver halide emulsions coated on polyester supports, which emulsions do not tend to fog.

One object of our invention is to provide photographic elements comprising photographic silver halide emulsion coated on polyester film base, which emulsion is protected against fogging caused by contaminants in the film base. Another object of our invention is to provide fog inhibiting agents for photographic silver halide emulsions which prevent fogging of the emulsion when coated on the polyester film base. Other objects of our invention will appear herein. V

These and other objects of our invention are accomplished by providing a polyester film base having a photographic silver halide emulsion thereon containing as an antifoggant a compound selected from the group consisting of parabanic acid, hydantoin and compounds having the following general formula:

3,287,135 Patented Nov. 22, 1966 'ice wherein Z represents the atoms required to complete a heterocyclic ring, such as R and R each are selected from the group consisting of H, alkyl, such as methyl, ethyl, :propyl, butyl, amyl, octyl, decyl and dodecyl, substituted alkyl, such as carboxyethyl, sulfopropyl or sulfobutyl, aryl, such as phenyl or naphthyl, and substituted aryl, such as benzyl; and monoacyl and diacyl derivatives of compounds having the above general formula, such as the monoand di-acetyl, propionyl, butyryl, valeryl, caprylyl, capryl and lauryl derivatives of such compounds; Typical specific useful compounds having the above general formula include urazole, 4-phenyl urazole, l-phenyl urazole, 4-ethyl urazole, maleic'acid hydrazide and phthalic acid hydrazide. The structural formula of the monoacyl and diacyl derivatives of compounds having the above general formula is not known; specific useful examples of such compounds are diacetyl derivatives of urazole and 4-phenyl urazole. A method for preparing the latter compounds is described in Chemical Abstracts, vol. 50, page 12033.

We have found that the emulsions of the photographic elements of our invention are effectively protected against the fogging caused by the contaminants present in polyester film base, and that the sensitometric characteristics of the emulsions are not adversely affected by the fog inhibiting agents of the invention.

Our invention will be further illustrated by the following examples. In these examples, silver bromoiodide emulsions were coated on a poly(ethylene terephalate) film support which contained catalyst residue and acidic by-products (believed to include acidic aldehyde compounds). For comparative purposes, the same emulsion was also coated on cellulose triacetate film base and tested. Fog inhibiting agents were incorporated in the emulsions and the stabilizing action was determined by expos ing the samples when fresh and after incubation for one Week at F. and 15% relative humidity, and developing for the time indicated in the following developer:

Grams Methyl p-aminophenol sulfate 2.2 Hydroquinone 8.8 Anhydrous sodium sulfate 72.0 Anhydrous sodium carbonate 48.0 Potassium bromide 4.0

Water to 1.0 liter.

Speeds were measured in terms of 30/E where E is the exposure, at 0.85 density units above fog. The results of these tests are tabulated in the following tables.

TAB LE 1 1 wk. at 120 F./ Dev. Rela- Net 15% Eli. Support Antifoggant Time tive Gamma Fog Speed Rela- N et tive Fog Speed Cellulose Acetate 3 100 2.8 0. 04 132 0. 14 6 118 2. 7 0. 05 135 0. 16 Polyethylene Terephthalate-. 3 118 2. 7 0.07 1. 38 a 6 135 2. 65 0. 09 2. 24 Do Urazole 3 105 2. 9 0. 06 129 0. 05 6 129 2. 85 0. O8 159 0. 08 Do Hydantoin 1 3 112 2. 7 0. 05 138 0. 44 6 141 2. 7 0. 07 126 0.92 Do Parabanic acid 3 115 2. 75 0. 05 120 0.73 6 141 2. 7 0. 08 1. 53

As may be seen in the foregoing table, urazole subaflFected other sensitometric characteristics of the emulstantially eliminates fog caused by the contammants sion. Tl'llS is illustrated in Table 3.

TABLE 8 1 wk. at 120 F./15% R.H. Support Antifoggant Dev. Relative Gamma Net Fog Time Speed Relative Net Fog Speed Cellulose Acetate. 3 100 3. 0. 0. 10 6' 129 2. 85 0. 07 0. 12 Polyethylene Terephtha1ate.. 3 118 2. 7 0. 11 0. 87

6' 148 2. 0. l4 1. 85 Do 3.5 g. 4-hydroxy-6-methyl-1,3, 3 129 2. 5 0. 20 1. 06 3a,7-tetrazaindene. 6 159 2. 3 0. 27 1. 96 Do 0.6 g. 6nitr0benzimidazole- 3 44 3. 05 0. 02 0. 08 6 2. 95 0. 04 0. 81

present in polyester film base and hydantoin and parabainic acid substantially reduce such fog. It is also shown that these antifoggants function without substantially altering other sensitometric characteristics of the emulsion.

As may be seen in Table 3 above the tetrazaindene compound (which functions as a strong antifoggant in was coated on polyester film base,.and fi-nitrobenzimidab As may be seen in the above table, rurazole and 4-substituted urazole compounds substantially eliminate fog caused by contaminants in polyester film base without adversely affecting other sensitometric characteristics of the emulsion. The results in Table 2 are based on a development time of 6 minutes.

The highly unexpected nature of our invention is shown by the fact that many conventional antifoggants were incorporated in emulsions which were coated on polyester film base, but that such antitoggants utterly failed to eliminate fogging of the emulsion caused by contaminants in the polyester film base, or adversely ole, while reducing fog, was unacceptable since it substantially lowered the speed of the emulsion.

In another series of examples,;a coarse grain silver bromoiodide gelatin emulsion of the type used for screen X-ray materials was prepared and divided into several- Test compounds were added to separate porportions. tions of this emulsion in the concentrations shown in the following table. Each portion was coated on a poly(ethylene terephthalate) film support (Kodak Estar). A sample of each coating was exposed on an Eastman 1B sensitometer and processed for 6 minutes in Kodak. De-

veloper D-l9b. Separate samples of each coating were incubated and processed in a similar manner. The following results were obtained:

TABLE 4 1 wk. Incuba- Fresh tion 120 F., Antiioggant, 0.01 RH. Support mole/mole Ag Rel. Fog Rel. Fog Speed Speed Cellulose Acetate" 0. 04 129 0. 07 Estar 115 0.08 1.84 Do Maleic acid hydra- 118 0. 08 132 0.11

Z1 8. Do Phthalic acid hy- 118 0. 05 159 0. 18

drazide. Do Diacetyl derivative 82 0.05 115 0. 17

ofurazole. Do Diacetyl derivative 107 0.06 0.21

of 4-phenyl urazole. Do 4-phenyl urazole- 102 0. 06 112 0.11 Urazole 0. 09 148 0. 10 Phthalimide 115 0. 0 1. 98 126 0. 2. 00 110 0. 58

As may be seen in the above table, the compounds in accordance with the invention eifectively reduced fog caused by contaminants in the polyester film base, whereas phthalimide, which is closely related to the compounds of the invention, completely failed to reduce such fog.

Further examples were conducted in which a medium grain silver bromoiodide emulsion was prepared and divided into several portions. Test compounds were added to separate portions of this emulsion in the concentrations shown in the following table. Each portion was coated on a poly(ethylene terephthalate) film support (Kodak Esta-r). A sample of each coating was exposed on an Eastman l-B sensitometer and processed for 36 minutes in Kodak Developer DK-SO. Separate samples of each coating were incubated and processed in a similar manner. The following results were obtained:

The results in Table 5 show that 4-ethyl urazole was an effective inhibitor of fog caused by contaminants in the polyester film base, whereas the closely related compounds ethyl-3-ethyl carbamyl carbozoate and ethyl-3-(l-naphthyl)carbamyl carbozoate failed to reduce such fog.

The following example illustrates that cyclic hydrazides also will control the fog of incorporated coupler emulsions coated on a polyethylene terephthalate support.

A red sensitive sulfur-gold sensitized silver bromoiodide gelatin emulsion was prepared containing an incorporated phenolic cyan coupler of the type described in US. Patent 2,474,293. The emulsion was divided into two parts. Urazole was added to one part at a concentration of 3 g./mole of silver halide. The emulsions were coated on a cellulose acetate support and also on a polyethylene terephthalate support (Estar). A sample of each coating was exposed on an intensity scale sensitometer and color developed in the usual manner with the following results.

This invention is generally applicable to silver halide emulsions but is especially useful with silver bromoiodide emulsions, particularly with high speed bromoiodide emulsions. The special antifoggants of the invention are most useful in concentrations of from about 0.01 to about 5 g. per gram moleof silver halide in the emulsion. Optimum concentrations of fog inhibiting agent are about 0.05 to 3.5 g. per gram mole of silver halide.

The film supports employed in the photographic elements of the invention are the polyester film supports including the polymers composed of bi-functional dicarboxylic acids and glycol substituents, such as polyesters prepared from 1,4-cyclohexanedimethanol and terepht-halic acid. Especially useful film supports are poly(alkylene terephthalate), poly(ethylene terephthalate) being particularly suitable. In the manufacture of such polyester film supports, for example, by the method described in British Patents 578,079 or 740,381, various side reaction products are formed which remain in the film and act as contaminants which have a tendency to cause fog when photographic silver halide emulsions are coated thereover. Although several contaminants may be present in the polyester support which are detrimental to silver halide emulsions, it is believed that the most serious fogcausing contaminants areacidic compounds containing aldehyde groups. The invention is broadlyapplicable to emulsions coated on polyester film base which contain contaminants tending to cause fogging of silver halide emulsions. Polyester film suitable for photographic supports may be from about 1 to 15 mils thick, and preferably are about 2 to 11 mils thick.

The emulsion of the photographic element of the invention may contain conventional emulsion addenda, e.g., sensitizers, coating aids, ultraviolet absorbers and the like. While it is preferred to employ gelatin as the hydrophilic carrier for the present emulsions, any of the well known gelatin substitutes such as polyvinyl alcohol, polyacrylamide, cellulosic materials and the like, and mixtures thereof, can also be used.

We have also found that fogging of emulsions coated on polyester supports may be prevented by incorporating the compounds described on page 2 in a layer, such as a gelatin colloid layer or a subbing layer, between the polyester support and the emulsion.

The invention has been described in detail with particular reference to preferred embodiments thereof but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A photographic element comprising a silver halide emulsion coated on a linear polyester film support, which polyester contains contaminants which tend to cause fogging of the silver halide emulsion, said emulsion containing a fog-stabilizing quantity of a compound selected from the group consisting of hydantoin; parabanic acid; compounds having the following general formula:

wherein Z represents the atoms required to complete a heterocyclic ring, and R is selected from the group consisting of H, alkyl, substituted alkyl, aryl and substituted aryl; and the monoacyl and diacyl derivatives of compounds having the above formula.

2. A photographic element comprising a light sensitive silver halide emulsion coated on a poly(ethylene terephthalate) film support, said support containing contaminants which tend to cause fogging of the emulsion, said emulsion containing a stabilizing quantity of a compound selected from the group consisting of hydantoin; parabanic acid; compounds having the following general formula:

wherein Z represents the atoms required to complete a heterocyclic ring, and R is selected from the group consisting of H, alkyl, substituted alkyl, aryl and substituted aryl; and the monoacyl' and diacyl derivatives of compounds having the above formula.

3. A photographic element omprising a light sensitive silver halide emulsion containing about 0.05- .0 g. urazole per gram mole of silver halide, said emulsion being coated on a poly (ethylene terephthalate) film support, which support contains contaminants which tend to cause fogging of the emulsion.

4. A photographic element comprising a light sensitive silver halide emulsion containing about 0.05-5 .0 g. 4-phenylurazole per gram mole of silver halide, said emulsion being coated on a poly(ethylene terephthalate) film support, which support contains contaminants which tend to cause fogging of the emulsion.

5. A photographic element comprising a light sensitive silver halide emulsion containing about 0.05-5 .0 g. 4-ethylurazole per gram mole 'of silver halide, said emulsion being coated on a poly(ethylene terephthalate) film support, which support contains contaminants which tend to. cause fogging of the emulsion.

6. A photographic element comprising a light sensitive 1 compound which stabilizes against fog is present in a layer wherein Z represents the atomsrequired to complete a heterocyclic ring, and R is selected from the group consisting of H, alkyl, substituted alkyl, and aryl and substituted aryl; and the monoacyl and diacyl derivatives of compounds having the above formula.

8. The photographic element of claim 7 wherein said interposed between said polyester support and said emulsion.

9. The photographic element of claim 8 wherein said compound which stabilizes against fog is maleic acid hydrazide.

References Cited by the Examiner UNITED, STATES PATENTS 2,708,161 5/1955 Jones et al. 96-109X 2,708,162 5/1955 Carroll et al. 96109-X 2,893,896 7/1959 Beeber et al. 9687 X 2,955,038 10/1960 Smith 9687 X 3,123,492 3/1964 Malfet 9687 X NORMAN G. TORCHIN, Primary Examiner.

I. H. RAUBITSCHEK, Assistant Examiner. 

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SILVER HALIDE EMULSION COATED ON A LINEAR POLYESTER FILM SUPPORT, WHICH POLYESTER CONTAINS CONTAMINANTS WHICH TEND TO CAUSE FOGGING OF THE SILVER HALIDE EMULSION, SAID EMULSION CONTAINING A FOG-STABILIZING QUANTITY OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDANTOIN; PARABANIC ACID; COMPOUNDS HAVING THE FOLLOWING GENERAL FORMULA: 